What is the Chemical Makeup of Stem Cells and How Can We Engineer Them?

[cronxeh]

As I'm watching the PBS presentation about stem cells ( http://www.pbs.org/wgbh/nova/sciencenow/3209/04.html ) and the debate on whether we should use the stem cells for research or not, I wonder what is the chemical make up of those stem cells. It is obvious that it is a DNA molecule, so it is in the domain of polymer chemistry.

My question is, how can we achieve that state of intelligence where we don't need to use biological principles to grow stem cells, but could make it into a routine chemical engineering process by developing those stem cells in a batch, in massive quantities?

 

[pattylou]

We can't create an entire cell yet, especially not a eukaryotic cell. To do so would go beyond polymer chemistry.

Stem cells are important because (1) they can be perfect genetic matches for individuals needing some sort of cell-based treatment and (2) they have so much plasticity - they can develop into a host of other cell types.

DNA synthesis technology, at present, allows us to synthesize stretches of (if I recall) hundreds of bases. A human genome, on the other hand, is... billions? of bases long. Also, there are errors that creep into synthetic DNA, more easily than into your cell's DNA.

So, it's not really a viable idea at the moment to create the DNA you need in a lab. but if it were, there would be additional problems.

Simple artificial cells (simple bacteria with very small genomes) are starting to be made by Craig Ventor's group. I forget the reason he's doing this. But a simple bacterium is only a miniscule fraction of the complexity of a eukaryotic cell - which is what a stem cell is. A eukaryotic cell has organeles, is much more massive, the DNA and cellular chemistry is present in a particular state which is precisely what *allows* the cell to be pluripotent, etc.

I think it is more liklely that adult stem cell technology will reach the end you seem to be looking for; also in other countries embryonic stem cell technology will continue to move forward.

 

[Monique]

The key is that you can reprogram cells, theoretically you can take an adult cell and give it the right cues that turn it into a stem cell with different potentials. Right now we use cloning to reset adult cells and make them pluripotent, if you pass a nucleus through an oocyte several times you can grow a new organism out of it.

Researchers are trying to figure out what defines a stem cell, it is a complicated system and requires the right signals intrinically AND extrinsically (a certain niche).

 

[selfAdjoint]

Simple artificial cells (simple bacteria with very small genomes) are starting to be made by Craig Ventor's group. I forget the reason he's doing this.

Rather than creating artificial bacteria, as he originally contemplated, Venter is now trying to "reprogram" an existing simple bacterium by removing its DNA and replacing it with artificial DNA. The idea is to create organisms with totally artificial metabolisms that can do industrial things like consume waste.

 

[pattylou]

Ah. Thanks.

Wisconsin? I earned my PhD in Madison, 1994, Dept. of Bacteriology. Have we met?

Toddling off to see your journal...